1. Technical Field
This invention relates generally to the field of electronic digital imaging and, specifically, to such imaging systems that utilize a light source write head to record information by scanning photosensitive media.
2. Background Art
Electronic digital imaging, such as for example in copiers and/or printers, is accomplished by modulating the intensity of a light beam that forms a writing spot on photosensitive media as the beam moves relative to the photosensitive media. One type of electronic digital imager uses a modulated array of light emitting diodes (LED's) positioned on a write head assembly resident on a rotor which is simultaneously rotated about a fixed axis and linearly translated past stationary photosensitive recording media mounted on the inner surface of a cylindrical "support shoe" to form a plurality of writing spots moving across the photosensitive material in a fast scan direction and in a slow scan direction, such as disclosed in commonly assigned, co-pending U.S. patent application Ser. No. 08/371,241, entitled DIGITAL PRINTER WITH SUPPORT SHOE AND TRANSLATABLE MEDIA GUIDE MEMBER THEREIN filed in the name of M. Bridges on Jan. 11, 1995. The disclosure of the Bridges patent application is hereby specifically incorporated herein by reference.
Imagers such as disclosed in the Bridges application must be factory-focused onto the predicted medial surface. It may be desirable from time-to-time to adjust the focus of the optical system such as to accommodate media of different thicknesses. Projection optics that can be re-focused relative to the media support enable the use of photosensitive media of multiple thicknesses while using the same lens assembly.
When using imagers such as disclosed in the Bridges and the Kiesow applications, the optics must remain focused under high rotational gravitational forces, and yet be easily re-focused in the field. Dismounting the lens during LED array changes causes a loss of focus, so provision must also be made for easy and repeatable replacement of the LED array. The optical elements must be light weight to minimize inertia because they are mounted on a spinning rotor.